Fig. 2. Schematic of the hood infiltrometer (not to scale). The effective pressure head on the soil surface can be determined with a precision of 1 mm from the difference of the height of the water level in the standpipe and the negative pressure head at the U-tube manometer. The zero point of the scale of the standpipe is at the soil surface (U_S = negative pressure at the U-tube manometer, H = height of the water table in the standpipe, H_K = infiltration chamber height, and T = submergence depth of the air pipe).